Method of processing lubricating



Patented July 17, 195i w OIL BY TREATING WITH sULFURIo ACID, APHOSPHORUS. SULFIDE AND "A BASE AND THE RESULTING PRODUCTS J 1 1. D.Bartlcson, East Cleveland, Ohio, assignor to The Standard Oil Company,Cleveland, Ohio,

acorporation of Ohio No Drawing. Application May 29, 1948,

$erial No. 30,207

18. Claims. (01. 25,232..

This invention relatesto processes of. improving hydrocarbon baselubricants, and more particularly to the treatment of hydrocarbonlubricants with sulfuric acid, then with a small amount of a phosphorussulfide, and following this by the treatment thereof with a base, andincluding a.

clay treatment, to formlubricants having. im-

proved properties, especially as to corrosion,

thetically prepared or which maybe derived. from.

natural sources, such as petroleum. For many purposes so-called.additives? mustbe. included with the hydrocarbon in order to. provide alubris cant having suitable characteristics. This is especially soin.the case of acid. refined oils. with detergent properties.

Generally. the inclusion. ofv

The treatment of the hydrocarbon oil with sul furic acid may be carriedout in the conventional these additives is associated. witha highercost. of

the finished lubricant. The preparation. of afine ished. lubricant.directly from hydrocarbon stock. by a chemical finishing; or refiningprocess (which does not involve solvent-refining or a detergentadditive) at a. commercially interesting cost. has been a particularlybaffiing: problem. to the art.

In, accordance with. the. invention, it. has. been. found thathydrocarbonlubricating; oil stock may be refined by treatment withsulfuric acid. inthe conventional manner, andthenfurther refined bytreatment withasmallamount of a phosphorus sulfide, and. following thiswith a metaljor nitro.-.

gen base treatment; and the resulting refined productis animproved;lubricant; i. e., a chemical finished. or refined. lubricant. A separateclay. treatment step is included in. thefiprocess at. a. stage. afterthe sulfuric acid refining step, preferably before. the phosphorussulfide refiningv step.

Such lubricants ar su able vfor us manner, e. g., using from 1 to 100lbs. of acid per barrel of oil, at a treating temperature in the; rangeof 32 to 300 F. A sludgeror acid layer is. removed. This step, has beenlong and well:- known in the art.

The further refining of the resulting hydrocarbon oil with thephosphorus sulfide may be conducted with direct admixture, or, ifvdesired, by their admixture in the presence of a diluent which; may besubsequently removed. Generally a diluent is not necessary. The reactionor treatment is usually complete. in about 10 hours or less time,generally 1 to 2 hours. lhe treating time is a. function of thetemperature, the amount of sul:-- fide that is to react, the subdivisionof the re.- actants, the efficiency of mixing the reactants, and thelike.

The hydrocarbon lubricant stock is reacted with the phosphorus sulfidein a ratio of from about 0.1 to about 0.75% by weight, based on theweight of the hydrocarbon stock, desirably about 0.25 to about 0.6%, andpreferably about 0.4 to 9.5%. If:- a higher amount of the sulfide isused, such as 1 some of the characteristics of the resulting, prod-- ucta Worse th n t e i i l oca bon o especially the viscosity increase. At.least 0.1% of the sulfide should be usedto achieve the results desi n acomm i i ltho g mall amounts show improvement.

The treatm n of t h dr c rb n w t t ph r s' u fi-d m e carr ed o t in hrmoen e r a s ce of a r r in a o he 9iinert Q n -deleteriou $3. 5. 1 atr gen-o H I may a e ar ou u r ress re.

e. g., pressure of theinert gas or that generated he t e re ot o soa rod ou in a o d v e The su de t ating tem er ur varies w th he yd ocarbontoc ene a y the emp ature should be atleast 275? F., but should be belowthe temperature at which the reaction product would b d m o e A tem r tre in ho ran e of abo 36 i aboi i 4 F- is Pr f rred in many cases. Thetreated oil, before or after conversion to a base derivative or both,may be centrifuged or filteredtp'remove any by-products, sludge, orother .by-product material. If a volatile diluent is used, is may beremoved by evap-1 oration. t l

T a d an s lfid refin d o l s ext trea ed with a base derivative, suchas a metal compound.

The metal base may be one or more metal compounds, such as theirsulfides, oxides, hydroxides, carbides and cyanamides. The preferredmetals are group I, group II and group III metals of the periodic table,such as potassium, zinc, barium and aluminum. For particular services,the heavier metals have particular use, i. e. those below zinc in theelectromotive series, such as chromium, cadmium, tin, lead, antimony,bismuth, arsenic, and the like. The alkali and alkaline earth metals arepreferred and of these potassium has been selected for the examples inorder that they may all be comparative.

In the preparation of the above type base derivatives, the treatmentwith the base may be carried out at temperature in the range of about100 to about 350 F., a temperature in the range of about 180 F. to 250F. being preferred.

From about 0.25 to about 6.0 equivalents of the metal compound may beused per mol of the sulfide used in the sulfide treatment, preferablyabout 1.0 to about 3.0 equivalents. An equivalent is the quotient of amol divided by the valence of the metal concerned.

. The hydrocarbon lubricant stock to which the process is applied may bea raw oil, e. g., a fluid hydrocarbon having a viscosity at 100 F. of to500 centistokes such as that used in S. A. E. 10 to 50 oils. It may beobtained as a distillate or from synthetic material, such as petroleum,and oils produced by cracking, polymerization, hydrogenation, and thelike methods.

In order to illustrate and point out some of the advantages of theinvention, but in no sense as a limitation thereof, the followingspecific embodiments are included.

In these examples the hydrocarbon stock is a conventional Mid-Continentlubricating oil base stock, of -30 S. A. E. viscosity (#300 Red Oil). Itis treated with sulfuric acid (10-15 lbs. of 93% acid per barrel of oil)in a conventional manner, and the sludge or acid layer is separated. Thephosphorus sulfide is mixed with the acid refined hydrocarbonlubricating oil, in the amounts indicated in the following table, andagitated for 1 hour at 300 F. at atmospheric pressure. Then it is mixedwith the amount and kind of base (based on the weight of thehydrocarbon" stock) indicated in the following table, and agitated for 2hours at 250 F., at atmospheric pressure. A good yield is obtained,based on the hydrocarbon lubricating oil, and no sludge is formed.However, it is preferred to filter the final reaction product.

In Examples 1, 2 and 3, the hydrocarbon oil used was obtained from #300Red Oil, by treating with 10-15 lbs. of 93% sulfuric acid, and allowedto settle overnight; portions of the hydrocarbon layer thereof were usedin these examples. In Examples 4, 5 and 6, the Red Oil was similarlyacid treated and settled, and then the hydrocarbon layer was separatedand treated with 8 lbs. of clay per barrel of oil; portions of this oilwere taken prior to filtration and used in these examples. The oil usedin Examples '7, 8, 9, 10, 11 and 12 was similarly treated, but theportions were taken after filtration. In Examples 13, 14 and 15, #225Red Oil was used (a similar oil to the above, but of 20 S. A. E.viscosity), which was similarly acid treated, then clay treated andfiltered. The oil was treated with the kind and amounts of phosphorussulfide, and then base, as indicated in the following table. Thepreceding, or subsequent, or both separate 4 clay treatments are alsoindicated. The reac tion product is identified hereinafter by theexample number.

Kind and Amount cm in Exam 18 Clay in of Phosphorus Kind and f g poundsper Sulfide in Per Amount of H barrel er barrel oil Cent by Weight Basep oil of Hydrocarbon O 0.2% P 55 and 0.2% Pisa.

The Sohio corrosion test was used in evaluating lubricants made inaccordance with the invention. This test is described in a co-pendingapplication of E. C. Hughes, J. D. Bartleson, M. L. Sunday and M. M.Fink, which also correlates the results of the laboratory tests with aChevrolet engine test.

Essentially the laboratory test equipment consists of a verticalthermostatically heated glass test tube (45 mm. outside diameter and 42cm. long), into which is placed the corrosion test unit. An air inlet isprovided for admitting air into the lower end of the corrosion unit insuch a way that in rising the air will cause the oil and suspendedmaterial therein to circulate into the corrosion unit. The tube isfilled with an amount of oil to be tested which is at least suificientto submerge the metals being tested.

The corrosion test unit essentially consists in a circular relativelyfine grained copper-lead test piece of t? O. D., which has a 4" diameterhole in its center (i.e.,shaped like an ordinary washer). The test piecehas an exposed copper-lead surface of 3.00 sq. cm. Of this surface area,1.85 sq. cm. acts as a loaded bearing, and is contacted by a part of thecylindrical surface of a hardened steel drill rod (14 diameter and at"long, and of 51-57 Rockwell hardness) The drill rod is held in a specialholder, and the holder is rotated so that the surface of the drill rodwhich contacts the bearing sweeps the bearing surface (the drill rod isnot rotated on its own axis and the surface of the drill rod whichcontacts the bearing is not changed).

The corrosion test unit means for holding the bearing and the drill rodis a steel tubing (15" long and ln g" O. D.) which is attached to asupport. A steel cup 1" long, 1 O. D. by i-" I. D.) is threaded into thesteel tube, at the lower end. The cup has a diameter hole in the bottomfor admitting the oil into the corrosion chamber. The copper-lead testpiece fits snugly into the steel cup and the hole in the test piece fitsover the hole in the steel cup. A section of steel rod in diameter and19" long) serves as a shaft and is positioned by 2 bearings which arefixedly set in the outer steel tubing, one near the top and one near thelower (threaded) end thereof. Several holes are drilled just above andjust below the lower bearing. The holes above the bearing facilitatecleaning the apparatus, while the holes below the bearing enable thecirculation of oil through the corrosion chamber. The drill rod holderis connected to the shaft byascents a. selfealiening yo e and pin g u lii i Th s a sures instantaneous, and cont nuous ieom t 01? t e drill rodbearing member a ains the b ,e surface at all times. A pulley is fittedto the top ofthe steel shaft and the shaft connected therethrough to apower source. The shaft rotated at about 5 R. P. and he Weig t of theshaft and a tached memb rs is a out 130 rams. Which is th ravi at o alfor e which rep.- resent the thrust on the h arin T e ai hit from theair inlet pumps t e o th ough he hamber conta n ng the test p ece andthrou h, the holes in th ste l tub n ratios of surfa e act e m ta to t evo me ofoil an nt na combust n. its; n: ine are ne rly quant tatively ulicated in the test e u ment- The tsmnsra urc us d. s a proxim te y thaof the ea in su ace, The rate o air fl w r volume o o l a u ted to t esame as. th average fo te t e i e n oocr: atiou- Of he ata y ic iicotsth se due t .9.1 uble iron are the. most important. They are empiricallyduplicated by the addition oi a soluble Those due to. lead trciniss d1pli dit' p ocedu e q by r ducin the us al 1 pint Q11 asa ticne ha e imat 4. our ntervals to z pint addit ons- Tiii n siifi on n'creaseshessvre ity oi tir test i s. and. dst is ney com on nts. particular yin. the ca e border ino oilsl ach, test. the lass sar s ar cleane b theusual chromic acid method, rinsed and dried. ire metal Harts ar Wasteswith. chloro orm an carb n. disuliislc, a d. 19911 has w th NQ- s. clothor steel W001. A new coigpctrlcad te s t I3.

found to correlate with the Chevrolet procedure 36-hour test are shownin the following table.

' bla 4. Temperature325. Oil sample107 cc. Air flow r'a.t e-,-'7-Qliters/hour Timehours Qatalysts Steel; copper-lead bearing: 3 sq. cm. ra f wh ch 1- om. s a. ocatin surf e: ferric Z-ethyl hexoate: 0.05% asFezQq in C, E benzene; lead bromide: 0 as preci itated p wd EQEWE. as mbLoa est t Q trees P 6.7 5.

By, extending the laboratory test to hours. it was found thatcorrelation with the. Chevrolet 72-hour test could be obtained.

At the close. of the test period, the extent ofcorrosion is. determinedbyreweighing the 001:5 rosion test piece and determining the change inweight due to the test. An accurate eyaluation of the laoqueringproperties of an oil is obtained by a visual rating system which isapplied to the outer surface of the corrosion unit steel tube and metalcup in much the same way that the piston skirt, cylinder wall, etc. ofan engine are rated for varnishes. The sludge rating of the engine issimulated by a visual rating of the insoluble materials and used oilwhich are coated on the lass test tube at the conclusion of the test.For both sludge and varnish rating a scale rating of A (best) to F(worst) is used.

A sufficient volume of used oil is obtained from, the test fordetermination of the usual used oil properties, such as pentaneinsolubles (sludge). viscosity increase, neutralization number and op.-tical density.

The term optical density, as used in the pres: ent disclosure,represents the standard logarithmic ratio of intensity of an incidentray falling on a transparent or translucent medium to the in tensity ofthe transmitted ray for a sample length of one meter and light of wavelength from 5100 to 5500. Angstroms.

The data. in the following tables typify the re, sults obtained in20-hour Sohio" corrosion tests on hydrocarbon lubricating oil basestock, andthe improved lubricants prepared therefrom in accordance withthe invention.

Table I s. A. E. Lubricant Example No... 20-30 1 2 3 4 5 H. -'l a.\,q-\- i A a r V Corrosion of Cu-Pb (in mg ns. weight loss of... 28. l3.0 3.8 5. 2 7. 5 4:9 Viscosity.LncrcaseKSUS)" 'L 938 217* 93 72 BentaneInsolublcs (in 895 200 222 213- 212 2 17 ncidNi i iribe'rfl; 5S9 1. 1.1; t l s Sludge a'ting. i Lacquer Rating" E O C 0+ 0- 0 Optical Dnsit260- 86.7 66. 4 77.9 86' 71. as; Con en (pe 0- 0- 0 274 9 38 45 t '26 e7 a 9 10 Lub i ntExam leNo (Blank) Corrosion of Ou-Pb (in mgms. Weightloss of). 28. 1 6. 6 6.1 7. 6 7. 9 9. 2 Viscosity Increase (SUS) 938 1764 141 134- Pcntane Insolubles (in m 895 152- 177' 173 209 Kc Niiinb'eil. 5539 k2 I}? 0.433 Sludge Rating. V v Lacquer Rating E- O- DO- D D'fificiiPDmMty-.. 260 103 106 146 134 16,4 Ash C nt nt (per centby g t gssuliat 9.0 .5? 0.39 0.69 0 57 0- Table III Lubricant-Example Nokfi gkf 13 14 16 Corrosion of Ou-Pb (in mgms.

weight loss of) 151. 8 7.1 6. 5 4. 2 Viscosity Increase (SUS) 1,390 100124 62 Pentane Insolubles (in mgm g.

of lubricant) 1, 395 99 118 68 Acid Number 5. 2 0. 74 1. 04 0.80 SludgeRating E A- A- A Lacquer Rating D A A A Ash Content (per cent byw ght,as

L sulfate) 0. 0 062 018 258 The above data show that the reactionproducts of the invention are clearly superior lubricants to the blankoil, and the great improvement in corrosion, viscosity increase, and'pentane insolubles is especially noteworthy. Example 1 (one claytreatment as last step)- showsespecially low corrosion; Example 6 (twoclay treatments) shows especially low viscosity increase; and Example 15(one clay treatment before the phosphorus sulfide refining step) showsespecially low pentane insolubles.

A similar example in which the oil is treated simultaneously withsulfide, KOI-I and clay shows the unsuitability of this method becauseof high viscosity increase. A subsequent and separate clay treatmentraises the viscosity increase. Simultaneous clay and sulfide treatmentfollowed by KOI-I'treatment is not satisfactory. These examplesdemonstrate the necessity of the steps recited in the order specified.

The 36-hour L-4 Chevrolet engine test was also used in comparing theoils of Examples 5, 6, 8, '11 and 12. In this test, new piston rings andtwo new copper-lead bearing inserts are installed in the motor prior toeach test. The engine is a conventional Chevrolet engine with 216.5 cu.in. piston displacement and a compression ratio of 6.5 to 1. The engineis operated at 3150 R. P. M. with a load of 30 B. I-L'P. and at atemperature at the jacket outlet of 200 F. The lubricating oiltemperature is maintained at 265 F. for an S. A. E. 10 grade oil, and at280 F. for oils of S. A. E. 30 to 50 grades. The fuel used contains from2.5 to 3.0 ml. of tetraethyl lead per gallon] Besides the weight loss ofthe test bearings, deposits in the power section, and properties of theused oil, sampled near the middle and also at the end of the test, areexamined. The following results were obtained.

Table IV LubricantExample N o 5 6 8 11 12 Overall Rating 68.75 80.50 86.2s 84. 2a 93. 50 Bearing Corrosion (rngms/ 7 bearing half-shell) 74 70176 232 Viscosity Increase (SUS) -24 38 -72 80 63 Pentane Insolubles (inper cent by weight of the oil) 3. 84 2.04 1.89 2. 73 2.66 Acid Number 2.2 0.97 1.55 1. 45 0.89

By comparable procedures, using any known comparable phosphorus sulfide,or amount of phosphorus sulfide, or hydrocarbon lubricating oil stock,within the broad types and ranges as indicated hereinbefore, comparableimproved lubricants are obtained.

If desired, the improved lubricants of the invention may be used inblends together with other lubricants or lubricant agents, e. g., withsoap or the like in a grease. If desired, an agent for improving theclarity of the oil may be included, e. g., lecithin, lauryl alcohol, andthe like. If desired,- an agent for preventing foaming may be included,e. g., tetra-amyl silicate. an alkyl ortho-carbonate, ortho-formate orortho-acetate, or a polyalkyl silicone oil.

In view of the foregoing disclosure, variations and modifications of theinvention will be apparent to those skilled in the art, and it isintended to claim such variations and modifications broadly, except asdo not come within the scope of the appended claims.

I claim:

1. A method of processing lubricating oil stock consisting essentiallyof hydrocarbon material to yield an oil having improved inhibition tooxidation in service, whch method comprises treating said stock withsulfuric acid in a conventional manner, then treating the resultingacid-refined hydrocarbon with an amount of a phosphorus sulfide in therange of about 0.1 to about 0.75% by weight at a temperature in therange of about 275 to 450 F., then with an amount of a base in the rangeof about 0.25 to 6.0 equivalents per mol of the sulfide, and includingat least one separate clay-treating step subsequent to the acid-refiningstep.

2. The method of claim 1 wherein the phosphorus sulfide is phosphoruspentasulfide, and the base is a metal base.

3. The method of claim 1 wherein the claytreating step is just prior tothe phosphorus sulfide treating step. I

4. The method of claim 1 wherein an amount in the range of about 0.25 toabout 0.6% of phosphorus sesquisulfide is used as the phosphorus sulfideand the treatment therewith is at a temperature of about 300 to 450 F. I

5. The method of claim 4 wherein the claytreating step is prior to thephosphorus sesquisulfide treating stepgand an amount of potassiumhydroxide in the range of about 0.1 to about 1.0%

is used as the base.

6. The method of claim 4 wherein an amount of potassium hydroxide in therange of about 0.1

. .to about 1.0% is used as the base, and the claycorrosion; and thisdata indicates that this ratio of P2155 and KCH is particularlydesirable.

7 claim 4.

treating step follows the base-treating step.

'7. The method of claim 3 wherein the phosphorus sulfide is phosphoruspentasulfide, and

the base is a metal base.

8. The method of claim 7 wherein the claytreating step is subsequent tothe metal base treating step.

9. The method of claim 8 wherein an amount in the range of about 1.0 to3.0 equivalents of potassium hydroxide is used as the base.

10. A lubricant obtained by the process of claim 1.

11. A lubricant obtained by the process of claim 2.

12. A lubricant obtained by the process of claim 3.

13. A lubricant obtained by the process of 14. A lubricant claim 5.

15. A lubricant claim 6.

16. A lubricant claim 7.

17. A lubricant claim 8.

18. A lubricant claim 9.

9 obtained by obtained by obtained by obtained by obtained by the the

the

the

the

DIOCESS process process of 5 process process JOHN D. BARTLESON.

10 REFERENCES CITED The following references are of record in the fileof this patent:

UNITED STATES PATENTS Number Name Date Petroff Feb. 17, 1914 White Apr.6, 1943 Musselman Jan. 22, 1946 Hughes Apr. 16, 1946 Noland Apr. 29,1947

1. A METHOD OF PROCESSING LUBRICATING OIL STOCK CONSISTING ESSENTIALLYOF HYDROCARBON MATERIAL TO YIELD AN OIL HAVING IMPROVED INHIBITION TOOXIDATION IN SERVICE, WHICH METHOD COMPRISES TRATING SAID STOCK WITHSULFURIC ACID IN A CONVENTIONAL MANNER, THEN TREATING THE RESULTINGACID-REFINED HYDROCARBON WITH AN AMOUNT OF A PHOSPHORUS SULFIDE IN THERANGE OF ABOUT 0.1 TO ABOUT 0.75% BY WEIGHT AT A TEMPERATURE IN THERANGE OF ABOUT 275* TO 450* F., THEN WITH AN AMOUNT OF A BASE IN THERANGE OF ABOUT 0.25 TO 6.0 EQUIVALENTS PER MOL OF THE SULFIDE, ANDINCLUDING AT LEAST ONE SEPARATE CLAY-TREATING STEP SUBSEQUENT TO THEACID-REFINING STEP.